1. Field of the Art
This invention relates to a video microscope, and more particularly to an improvement in a video microscope adapted to optionally and continuously vary image pickup magnification of an object or magnifying power at which an image of an object to be observed is to be picked up over a wide range without requiring replacement of a lens.
2. Description of the Related Art
A conventional video microscope of such a type is generally constructed in a prefocus type manner of keeping a lens system stationary with respect to an object to be observed (hereinafter referred to as "observed object"). Unfortunately, such construction causes a variation in enlargement (reduction) magnification or magnifying power of an image to be picked up to require replacement of the lens system itself.
Also, as a means for varying enlargement (reduction) magnification of an image to be picked up, a zoom lens system has been often employed.
The above-described prefocus construction for varying the enlargement (reduction) magnification or magnifying power is inconvenient, because replacement of the lens system is required every time the variation is to be carried out. Also, the prefocus construction has another disadvantage that it is required to previously prepare lens systems suitable for enlargement (reduction) magnification desired. The latter means or zoom lens arrangement fails to vary the magnification or magnifying power over a wide rage because a variation in magnifying power of the zoom lens system is limited to a narrow range as small as 3 to 4 magnifications.